2018/03/05 by Achim Kempf
Mathematics · Physics and Astronomy · #Algorithm #Asymptotic safety in quantum gravity #Background independence #Black Holes and Theoretical Physics #Causal sets #Cosmic microwave background #Cosmology and Gravitation Theories #Mathematics #Noncommutative and Quantum Gravity Theories #Physics #Planck #Quantization (signal processing) #Quantum #Quantum field theory in curved spacetime #Quantum gravity #Quantum mechanics #Spacetime #Spacetime topology #Theoretical physics #gr-qc
paper · pdf · doi:10.1007/s10701-018-0163-2
Based on an invited presentation at the Lemaitre Workshop (9-12 May 2017, Vatican Observatory)
arxiv created 2018/03/05 · openalex publication_date 2018/04/05 · arxiv updated 2018/05/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We review connections between the metric of spacetime and the quantum fluctuations of fields. In particular, we discuss the finding that the spacetime metric can be expressed entirely in terms of the 2-point correlators of the fluctuations of quantum fields. We also discuss the open question whether the knowledge of only the spectra of the quantum fluctuations of fields suffices to determine the spacetime metric. This question is of interest because spectra are geometric invariants and their quantization would, therefore, have the benefit of not requiring the modding out of the diffeomorphism group. Further, we discuss the fact that spacetime at the Planck scale need not necessarily be either discrete or continuous. Instead, results from information theory show that spacetime may be simultaneously discrete and continuous in the same way that information can. Finally, we review the finding that a covariant natural ultraviolet cutoff at the Planck scale implies a signature in the cosmic microwave background (CMB) that may become observable.